This solid square block of stone is the Lotrščak Tower, and it has guarded the southern gate of Gradec, the citizens' hill, for about eight hundred years. Its name is a lovely piece of history in itself. It comes from a Latin phrase meaning the thieves' bell, because a bell was hung here to signal the closing of the town gates each night. When that bell rang, if you were still outside the walls, you were locked out until morning, left in the dark with the actual thieves. So people learned to listen for it. But the tower does not ring a bell for you today. It fires a cannon. Every single day, at exactly noon, a cannon fires from a window in this tower, out over the rooftops of the city. It has done so for nearly one hundred and fifty years without missing a day. The original reason was beautifully practical. In a city with many churches and many bells, nobody could agree on the exact time, so the cannon was fired at noon to give everyone a single moment to set their clocks by. The church bell ringers would wait for the boom, then ring in unison. Now, why a cannon and not just a clock? For that there’s a legend, and it is a good one. The story goes that long ago, during the Ottoman wars, the defenders of Zagreb fired a cannon from this hill at the Ottoman camp across the river. And by sheer freakish luck, the cannonball flew all the way across the Sava, straight into the enemy camp, and landed smack in the middle of a platter of chicken being carried to the Ottoman commander. The story goes that he took this as such a terrifying omen, a single shot demolishing his lunch, that he packed up his entire army and fled. Did it happen? Almost certainly not, at least not like that. But the people of Zagreb loved the idea that their noon gun once won a war by ruining a general's dinner, and who am I to take that away from them? Here is my tip. Check the time. If noon is anywhere close, wait for it, right here. The cannon is loud, genuinely loud, so do not be alarmed, but hearing that boom roll across the city with your own ears is one of the great free experiences in Zagreb. Also, you can climb the tower if you would like to for a great view of the city but you’ll have to pay an entry fee. Now turn around, and you’ll find yourself at the top of a very short, very steep railway.